Themed SVG diagrams

The rules geography and agent CLI authentication figures now keep Mermaid source, explicit semantic theme manifests, standalone-adaptive SVGs, and host-runtime SVGs together. Their original hand-authored artwork remains available as fixed output, while the public filenames continue to provide no-JavaScript adaptive images.

Generation is deterministic through the pinned Mermaid CLI, @dev-centr/mermaid-svg-css-vars 0.1.2, and @dev-centr/themed-svg 0.1.1. The canonical diagram guidance now matches the implementation’s --themed-svg-<namespace>-…​ custom-property namespace.